Survival of airborne Stachybotrys spores

Viable spores of Stachybotrys atra are rarely encountered in samples of indoor
air. If they are detected, the accepted interpretation, in the context of
indoor air quality, is that there must be (and usually is) an active growth
site nearby as the spores do not survive for long once airborne.
Given this limited survival of airborne spores, what is the source of
infection which will initiate growth of Stachybotrys on, say, wallboard
which has become wet, in an otherwise dry, reasonably maintained building?
Any thoughts?
----------------------------------- * ----------------------------------
Austin Reade, Microbiologist Phone: (902) 424-8670
Innovacorp Fax: (902) 424-4679
101 Research Drive, PO Box 790 Internet: areade at nsrfc.ns.ca
Dartmouth, NS, Canada B2Y 3Z7